Background
China is an important production place of corn, and in recent years, along with the improvement of living standard and the gradual deepening of health care consciousness of people, corn oil as daily oil with high nutritional value gradually enters common people. Corn oil is an oil obtained by squeezing corn germ. Compared with the traditional oil, the corn oil is an oil product with high contents of linoleic acid, vitamin E, phytosterol and the like, so that the corn oil is taken as the healthy oil for realizing popularization and development since the corn oil is produced in China, and the market space, the edible people and the like are greatly increased. After being popularized for over ten years, the corn oil is popular with more and more consumers.
At present, the more commonly used vegetable oil and fat preparation technologies include a cold pressing method, a solvent extraction method of No. six, an aqueous enzymatic method and supercritical fluid extraction. The cold pressing method is an oil production technology for obtaining oil and cake meal with unchanged nutritive value and molecular structure by pressing oil without baking and blank rolling through a low-temperature oil press, and has the defect of low extraction rate; the supercritical fluid extraction method has high requirements on equipment, small equipment treatment capacity and difficult adaptation to large-scale production in the grease industry; the solvent extraction method is a process for extracting oil from oil under normal pressure by using normal hexane (also called solvent VI) as a solvent, the extraction process has the disadvantages of high temperature required by oil desolventizing and cake desolventizing procedures, large solvent consumption, easy pollution, high energy consumption, long-time high-temperature state of cake and high cake protein denaturation rate, and the water-enzyme method oil preparation is a plant oil extraction technology emerging in recent years, and the method utilizes machinery and biological enzyme to destroy cell walls of plant seeds and combines a water-solvent method to extract oil, so that the oil yield is low and the flavor is weak. Therefore, the search for a new process technology for extracting the oil with green, low consumption and high efficiency becomes a research hotspot in the field of oil extraction in recent years.
The subcritical extraction technology is a pressurized fluid extraction technology, when the technology is used for oil extraction, the work is carried out at normal temperature and under a certain pressure, and the used extracting agent exists in a gas form at normal temperature and normal pressure and exists in a fluid state under a pressurized state. Under the subcritical pressurization state, the molecular diffusion capacity of the extracting agent is enhanced, the mass transfer rate is accelerated, the permeability and the dissolving capacity of weak polar substances such as grease in materials are obviously improved, meanwhile, the low temperature or the normal temperature is adopted in the extraction process, the natural active ingredients of the extracted materials are fully reserved, the extraction process is isolated from the air, the reactions such as oxidation and the like of special materials cannot be caused, the target substances are completely reserved, the extraction pressure is low, the requirement on equipment is much lower than that of supercritical extraction, and the industrial mass production is easy to realize. Therefore, the subcritical extraction is regarded as a new oil preparation technology with wide green and environment-friendly prospect. The research of subcritical extraction technology starts from 1990 in China, and after more than thirty years of development, the technology has been industrially applied in the aspect of oil preparation at present, oil production processes such as soybean oil, peanut oil and rapeseed oil have been developed and produced successively, and the report of the technology for producing the corn oil is not seen yet.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the subcritical extraction method of the corn oil, which has the advantages of reasonable process, greenness, low consumption, high efficiency, safe and simple operation and can be used for large-scale production of the corn oil.
The technical scheme adopted by the invention for realizing the purpose is as follows: the invention provides a subcritical extraction method of corn oil, which comprises the following steps:
(1) crushing corn seeds to obtain germ powder, wherein the granularity of the crushed corn seeds is 40-60 meshes;
(2) primary extraction: adding ethane-isobutane-dimethyl ether into the germ powder as a subcritical extractant, extracting at 45 ℃ for 30 minutes each time, and performing countercurrent extraction for 3 times by adopting 3 groups of extraction tanks to obtain primary crude oil;
(3) secondary extraction: introducing carbon dioxide containing dimethyl ether and methanol into the corn oil residue after primary extraction at the flow rate of 5mL/min, extracting for 120-150min at the temperature of 40-45 ℃ and the pressure of 35-40MPa, and separating and recovering the carbon dioxide and the dimethyl ether to obtain secondary crude oil;
(4) and mixing the two crude oils, and refining to obtain the corn oil.
The subcritical extracting agent used by the invention is prepared from ethane-isobutane-dimethyl ether according to the volume ratio of 1: 1: 0.4-0.6.
Further, the feed-liquid ratio of the primary extraction is 1: 5 g/mL.
Further, the addition amount of the dimethyl ether accounts for 2-3% of the carbon dioxide; the volume ratio of the dimethyl ether to the methanol is 1: 0.3-0.5.
The invention has the beneficial effects that:
(1) the extraction process provided by the invention has the advantages of high extraction rate, small damage rate to nutrients and wide market prospect.
(2) The invention has high utilization rate of raw materials, can reserve the flavor and the nutrient content of corn seeds to the maximum extent, and can quickly desolventize, and the prepared finished oil has no solvent residue.
Detailed Description
The technical solution of the present invention is further explained and illustrated by the following specific examples.
Example 1
A subcritical extraction method of corn oil comprises the following steps:
(1) crushing corn seed germs to 60-mesh granularity to obtain germ powder;
(2) primary extraction: adding a subcritical extractant ethane-isobutane-dimethyl ether (volume ratio is 1: 1: 0.5) into the germ powder, wherein the material-liquid ratio of the germ powder to the subcritical extractant is 1: 5 g/mL; extracting at 45 deg.C for 30 min in each time by 3 groups of extraction tanks for 3 times in countercurrent to obtain primary crude oil;
(3) secondary extraction: introducing carbon dioxide containing dimethyl ether and methanol into the corn oil residue after primary extraction at a flow rate of 5mL/min, extracting for 150min at the temperature of 40-45 ℃ and under the pressure of 35-40MPa, and separating and recovering carbon dioxide and dimethyl ether to obtain secondary crude oil;
the addition amount of the dimethyl ether accounts for 2 percent of the carbon dioxide; the volume ratio of the dimethyl ether to the methanol is 1: 0.5;
(4) and mixing the two crude oils, and refining to obtain the corn oil.
Example 2
A subcritical extraction method of corn oil comprises the following steps:
(1) crushing corn seed germs to 60-mesh granularity to obtain germ powder;
(2) primary extraction: adding a subcritical extractant ethane-isobutane-dimethyl ether (volume ratio is 1: 1: 0.6) into the germ powder, wherein the material-liquid ratio of the germ powder to the subcritical extractant is 1: 5 g/mL; extracting at 45 deg.C for 30 min in each time by 3 groups of extraction tanks for 3 times in countercurrent to obtain primary crude oil;
(3) secondary extraction: introducing carbon dioxide containing dimethyl ether and methanol into the corn oil residue after primary extraction at a flow rate of 5mL/min, extracting for 120min at the temperature of 40-45 ℃ and under the pressure of 35-40MPa, and separating and recovering carbon dioxide and dimethyl ether to obtain secondary crude oil;
the addition amount of the dimethyl ether accounts for 3 percent of the carbon dioxide; the volume ratio of the dimethyl ether to the methanol is 1: 0.3;
(4) and mixing the two crude oils, and refining to obtain the corn oil.
Comparative example 1
A subcritical extraction method of corn oil comprises the following steps:
(1) crushing corn seed germs to 60-mesh granularity to obtain germ powder;
(2) primary extraction: adding a subcritical extracting agent ethane into the germ powder, wherein the ratio of the germ powder to the subcritical extracting agent is 1: 5 g/mL; extracting at 45 deg.C for 30 min in each time by 3 groups of extraction tanks for 3 times in countercurrent to obtain primary crude oil;
(3) secondary extraction: introducing carbon dioxide containing dimethyl ether and methanol into the corn oil residue after primary extraction at a flow rate of 5mL/min, extracting for 150min at the temperature of 40-45 ℃ and under the pressure of 35-40MPa, and separating and recovering carbon dioxide and dimethyl ether to obtain secondary crude oil;
the addition amount of the dimethyl ether accounts for 2-3% of the carbon dioxide; the volume ratio of the dimethyl ether to the methanol is 1: 0.5;
(4) and mixing the two crude oils, and refining to obtain the corn oil.
Comparative example 2
A subcritical extraction method of corn oil comprises the following steps:
(1) crushing corn seed germs to 60-mesh granularity to obtain germ powder;
(2) primary extraction: adding a subcritical extractant isobutane into the germ powder, wherein the ratio of the germ powder to the subcritical extractant is 1: 5 g/mL; extracting at 45 deg.C for 30 min in each time by 3 groups of extraction tanks for 3 times in countercurrent to obtain primary crude oil;
(3) secondary extraction: introducing carbon dioxide containing dimethyl ether and methanol into the corn oil residue after primary extraction at a flow rate of 5mL/min, extracting for 150min at the temperature of 40-45 ℃ and under the pressure of 35-40MPa, and separating and recovering carbon dioxide and dimethyl ether to obtain secondary crude oil;
the addition amount of the dimethyl ether accounts for 2-3% of the carbon dioxide; the volume ratio of the dimethyl ether to the methanol is 1: 0.5;
(4) and mixing the two crude oils, and refining to obtain the corn oil.
Comparative example 3
A subcritical extraction method of corn oil comprises the following steps:
(1) crushing corn seed germs to 60-mesh granularity to obtain germ powder;
(2) primary extraction: adding a subcritical extracting agent dimethyl ether into the germ powder, wherein the ratio of the germ powder to the subcritical extracting agent is 1: 5 g/mL; extracting at 45 deg.C for 30 min in each time by 3 groups of extraction tanks for 3 times in countercurrent to obtain primary crude oil;
(3) secondary extraction: introducing carbon dioxide containing dimethyl ether and methanol into the corn oil residue after primary extraction at a flow rate of 5mL/min, extracting for 150min at the temperature of 40-45 ℃ and under the pressure of 35-40MPa, and separating and recovering carbon dioxide and dimethyl ether to obtain secondary crude oil;
the addition amount of the dimethyl ether accounts for 2-3% of the carbon dioxide; the volume ratio of the dimethyl ether to the methanol is 1: 0.5;
(4) and mixing the two crude oils, and refining to obtain the corn oil.
Comparative example 4
A subcritical extraction method of corn oil comprises the following steps:
(1) crushing corn seed germs to 60-mesh granularity to obtain germ powder;
(2) primary extraction: adding a subcritical extractant ethane-isobutane-dimethyl ether (volume ratio is 1: 1: 0.5) into the germ powder, wherein the material-liquid ratio of the germ powder to the subcritical extractant is 1: 5 g/mL; extracting at 45 deg.C for 30 min in each time by 3 groups of extraction tanks under countercurrent for 3 times to obtain crude oil;
(3) refining the crude oil to obtain the corn oil.
Comparative example 5
A subcritical extraction method of corn oil comprises the following steps:
(1) crushing corn seed germs to 60-mesh granularity to obtain germ powder;
(2) primary extraction: adding a subcritical extractant ethane-isobutane-dimethyl ether (volume ratio is 1: 1: 0.5) into the germ powder, wherein the material-liquid ratio of the germ powder to the subcritical extractant is 1: 5 g/mL; extracting at 45 deg.C for 30 min in each time by 3 groups of extraction tanks for 3 times in countercurrent to obtain primary crude oil;
(3) secondary extraction: introducing carbon dioxide containing methanol into the corn oil residue after primary extraction at a flow rate of 5mL/min, extracting for 150min at 40-45 ℃ and under a pressure of 35-40MPa, and separating and recovering carbon dioxide and dimethyl ether to obtain secondary crude oil;
the addition amount of the methanol accounts for 3% of the carbon dioxide;
(4) and mixing the two crude oils, and refining to obtain the corn oil.
Comparative example 6
A subcritical extraction method of corn oil comprises the following steps:
(1) crushing corn seed germs to 60-mesh granularity to obtain germ powder;
(2) primary extraction: adding a subcritical extractant ethane-isobutane-dimethyl ether (volume ratio is 1: 1: 0.5) into the germ powder, wherein the material-liquid ratio of the germ powder to the subcritical extractant is 1: 5 g/mL; extracting at 45 deg.C for 30 min in each time by 3 groups of extraction tanks for 3 times in countercurrent to obtain primary crude oil;
(3) secondary extraction: introducing carbon dioxide containing dimethyl ether into the corn oil residue after primary extraction at a flow rate of 5mL/min, extracting for 150min at the temperature of 40-45 ℃ and under the pressure of 35-40MPa, and separating and recovering carbon dioxide and dimethyl ether to obtain secondary crude oil;
the addition amount of the dimethyl ether accounts for 3 percent of the carbon dioxide;
(4) and mixing the two crude oils, and refining to obtain the corn oil.
Effects of the embodiment
Firstly, the chemical components of the finished corn oil prepared in the examples 1-2 and the comparative examples 1-6 are detected by adopting a gas chromatography-mass spectrometry method, and the specific detection results are shown in the table 1.
TABLE 1
Secondly, the oil yield statistics of the corn oil extracted by the preparation methods provided in examples 1-2 and comparative examples 1-6 are shown in Table 2.
TABLE 2